Communication between neurons in the brain requires efficient calcium-triggered release of neurotransmitter from active neurons. Since the mechanisms of transmitter release have been highly conserved throughout evolution, molecular-genetic studies in fruit flies can reveal how mammalian neurons communicate without the expense or ethical considerations of mammalian studies. The current NSF project will examine how the neuronal calcium-binding protein, synaptotagmin, couples increased intra-neuronal calcium with neurotransmitter release. Synaptotagmin exhibits calcium-dependent interactions with cell membranes as well as with specific proteins. Using molecular techniques to generate mutant transgenic Drosophila, Dr. Reist and colleagues will determine the interactions that couple calcium-binding to efficient transmitter release. Actively adjusting the amount of transmitter released is thought to be a key mechanism mediating learning and memory in higher organisms. Thus, this work will provide critical scientific background required for translational studies aimed at improving neuronal communication in cases of neural dysfunction such as Alzheimer's disease. All transgenic fly lines generated will be made freely available to the scientific community. Dr. Reist has trained numerous undergraduate and graduate students and the implementation of this project will provide continued training opportunities for U.S. students. In addition, Dr. Reist participates in the International Brain Research Organization's visiting lecture team program and has taught students in China and Nigeria about the molecular mechanisms of transmitter release. As such, these studies will directly contribute to educational outreach in developing countries as well as within the United States.

Project Report

Intellectual Merit: Communication between neurons in the brain requires efficient calcium-triggered release of neurotransmitter from active neurons. Since the mechanisms of transmitter release have been highly conserved throughout evolution, molecular-genetic studies in fruit flies can reveal how mammalian neurons communicate without the expense or ethical considerations of mammalian studies. This NSF project examined how the neuronal calcium-binding protein, synaptotagmin, couples increased intra-neuronal calcium with neurotransmitter release. Synaptotagmin exhibits calcium-dependent interactions with cell membranes as well as with specific proteins, the SNARE proteins, required for transmitter release. Using molecular techniques to generate mutant transgenic Drosophila, Dr. Reist and colleagues determined that both of these interactions are required for efficient transmitter release. The interaction with membranes was found to be absolutely essential and disruption of this interaction was lethal. The interaction with the SNARE proteins was important for efficient neuronal communication as disruption of these interactions reduced transmitter release by 75%. Since adjusting the amount of transmitter released is thought to be a key mechanism mediating learning and memory, this work elucidating the basic mechanisms of synaptic transmission should promote translational studies aimed at improving neuronal communication in cases of neuronal dysfunction. Indeed, a current international collaboration, which was initiated under this grant, is aimed at determining the basic molecular mechanisms that underlie the symptoms of a familial peripheral motor neuron syndrome caused by a mutation in synaptotagmin. Broader impacts: During the course of this project three transgenic fly lines were generated. These will be made freely available to the scientific community promptly after publication of our findings. This project provided training for one female high school student, ten undergraduate (5 female, 4 minority) and three graduate (1 female) students in the United States. While supported by this grant, Dr. Reist participated in the International Brain Research Organization’s visiting lecture team program (http://ibro.info/professional-development/vltp-courses/). She taught students in Sri Lanka and Iraq (http://csu-cvmbs.colostate.edu/academics/bms/Pages/reist-neuroscience-education-developing-world.aspx) about the molecular mechanisms of transmitter release. As such, the studies supported by this grant directly contributed to educational outreach in developing countries. At an international meeting designed to bring clinical and basic scientists together, clinical scientist Dr. Hanns Lochmuller from Newcastle University heard Dr. Reist’s presentation of findings from this grant regarding the identification of molecular mechanisms of synaptotagmin function. When his colleague Dr. Rita Horvath subsequently discovered that a peripheral motor neuron syndrome in a familial group of patients was caused by a single amino acid substitution in synaptotagmin, Drs. Lochmuller and Horvath contacted Dr. Reist. Thus, we are currently developing Drosophila as a model system to determine the molecular mechanisms mediated by this amino acid.

Agency
National Science Foundation (NSF)
Institute
Division of Integrative Organismal Systems (IOS)
Type
Standard Grant (Standard)
Application #
1025966
Program Officer
Evan Balaban
Project Start
Project End
Budget Start
2010-08-01
Budget End
2014-12-31
Support Year
Fiscal Year
2010
Total Cost
$467,996
Indirect Cost
Name
Colorado State University-Fort Collins
Department
Type
DUNS #
City
Fort Collins
State
CO
Country
United States
Zip Code
80523